Brain Pathology Case of the Month - October 2000

MICROSCOPIC DESCRIPTION:

Histologically, all nodes and the thickened dura mater showed similar morphological features. Small nests of meningothelial cells were observed in the vicinity of chronic inflammatory infiltrate (Figs. 06 and 07). They featured ill-defined cell borders, oval nuclei and delicate chromatin pattern, and some of them showed rounded eosinophilic cytoplasmic protrusions into the nuclei. Whorl formations and psammoma bodies were moderate in number. Mitotic figures were absent. Surrounding the meningothelial nests, diffuse lymphocyte and plasma cell infiltrate and sparse Russell bodies were observed. No granulomatous reaction was seen. A few hemosiderin-containing macrophages were present. Some spinal roots were infiltrated microscopically. Immunohistochemically, the meningothelial component exhibited strong immunoreactivity for epithelial membrane antigen (EMA, Fig 08) and vimentin (Fig. 09). Within the infiltrate, type-B lymphocytes and plasma cells that were CD79a-positive predominated (Fig 10), and only a small number of CD30-positive-type T-lymphocytes could be found (Fig. 11).